Respiration

Proceedings of the 28th International Congress of Physiological Sciences, Budapest, 1980

I. Hutás, L. A. Debreczeni

• Publisher: Pergamon
• Year: 2013
• Print ISBN: 9780080268231
• eBook ISBN: 9781483163918
• Topic: Medicine
• Subtopic: Physiology

Advances in Physiological Sciences, Volume 10: Respiration focuses on the movements in respiratory research, including studies on the breathing process in humans; how respiratory muscles aid in respiration; and how various drugs affect breathing. The book also presents how respiratory muscles in humans, birds, and mammals function during different activities. The text also outlines the diseases that arise due to limited expiratory airflow and how muscles undergo fatigue. Divided into nine parts and organized into 77 chapters, the book further looks into the function of the lung during respiration through the comparison of the breathing patterns of humans, birds, and mammals. The text also elaborates how drugs are instituted in various laboratory exercises to determine their effects on the respiratory system in all the subjects mentioned. The book also identifies the different parts of the body that are involved in the breathing process. Readers and scholars who are interested in research concerning the trends in respiratory physiology will find this book interesting.

Comparative physiology of respiration: birds versus mammals

INTRODUCTION TO COMPARATIVE PHYSIOLOGY OF RESPIRATION: BIRDS VERSUS MAMMALS

J. Piiper, Abteilung Physiologie, Max-Planck-Institut für experimentelle Medizin, D-3400 Göttingen, FRG

Publisher Summary

This chapter presents a comparison of the physiology of respiration in birds and mammals. The phylogeny of birds and mammals is in many respects a parallel, convergent evolution leading to many important physiological characters shared by both such as high metabolic rate, enlarged scope for activity, and homoiothermy. A highly efficient gas exchange and transport system is a prerequisite for high aerobic metabolic rate. Therefore, lungs with large surface area and short air-blood distance, complete separation of arterialized and venous blood, and blood with high hemoglobin content are features common to mammals and birds. From evidence on few avian species, birds seem to be more tolerant of hypoxia than mammals, and some birds can survive and be active at extremely low O₂ pressures. In mammals, CO₂ tension (and pH) in arterial blood is a controlled variable, which is considered to be sensed by the central and peripheral chemoreceptors, located on the ventral surface of the brain stem and in the carotid and aortic bodies, respectively. In birds, however, there is good experimental evidence for the existence and functional importance of intrapulmonary CO₂ receptors.

From primitive reptiles (stem reptiles or cotylosaurs) evolved not only all the numerous and diversified groups of reptiles, of which crocodiles, turtles, snakes and lizards (and a single rhynchocephalian species) have survived, but also the vertebrate groups universally recognized as most advanced, birds and mammals. Thus birds and mammals are “glorified reptiles” representing the present end-points of the evolution of two reptilian branches, the archosaurian and the therapsid, respectively.

The phylogeny of birds and mammals is in many respects a parallel, convergent evolution leading to many important physiological characters shared by both like high metabolic rate, enlarged scope for activity, and homoiothermy (all of which are interdependent). A highly efficient gas exchange and transport system is a prerequisite for high aerobic metabolic rate. Therefore lungs with large surface area and short air-blood distance, complete separation of arterialized and venous blood, and blood with high hemoglobin content are features common to mammals and birds.

The conspicuous comparative anatomical difference in the design of the arterial system between birds and mammals (development of the aortic arch from the left 4th arterial arch in mammals, from the right 4th arch in birds) is well known. Less well known is the fact that the whole structure and function of the respiratory tract is thoroughly different in birds from that known from mammals. These anatomical features and their consequences for gas exchange will be analysed by MEYER et al.

The high O₂ (and CO₂) transport rate is ensured by high blood flow (cardiac output) and the high O₂ (and CO₂) carrying capacity of blood. An obvious difference is the absence of nucleus in mammalian erythocytes, its presence in avian red blood cells. Since the deformability of red cells has been recognized as an eminently important factor in the microrheology of mammalian blood, it is of particular interest to evaluate the rheological behavior of nucleated red cells. This is the topic of GAEHTGENS et al. in this symposium.

As far as known, from evidence on few avian species, birds seem to be more tolerant of hypoxia than mammals, and some birds can survive and be active at extremely low O₂ pressures. Therefore, a comparison birds/mammals of the mechanism of hypoxia tolerance, particularly of the hyperventilation induced by hypoxia through reflexes originating in arterial chemoreceptors, should be of particular interest and will be undertaken by BOUVEROT.

In mammals, CO₂ tension (and pH) in arterial blood is a controlled variable which is considered to be sensed by the central and peripheral chemoreceptors, located on the ventral surface of the brain stem and in the carotid (and aortic) bodies, respectively. In birds, however, there is good experimental evidence for the existence and functional importance of intrapulmonary CO₂ receptors (whose occurrence in mammalian lungs is controversial). FEDDE will present a short overview on avian intrapulmonary CO₂ receptors.

Obviously the respiratory gas transport system and its regulatory adjustments are expected to be dimensioned to the maximum physiological gas transport requirements rather than to resting metabolism. The typical activity of birds is flight. Recent achievements in the study of the cardiorespiratory system in flying birds will be summarized by BUTLER. Although running is more typically a mammalian activity, also birds can run, and experimental data on running birds will be compared to corresponding data obtained in various mammals by KILEY.

The elaboration of the modes of reproduction and of embryonic (fetal) adjustments are of eminent importance in evolution. The allantoic vessels and the chorioallantoic capillary plexus in birds is homologous to the umbilical vessels and to the fetal placental capillaries, respectively, in placental mammals. However, in bird’s egg, the “maternal side” of the placenta as well as the whole maternal organism is absent, being functionally replaced by the egg shell. Some consequences emerging from a comparison of respiratory gas transport between bird’s embryo and mammalian fetus will be summarized by METCALFE and BISSONNETTE.

A COMPARISON OF CHORIOALLANTOIC AND PLACENTAL RESPIRATION

James Metcalfe and John M. Bissonnette, Departments of Medicine and Obstetrics and Gynecology University of Oregon Health Sciences Center, Portland, Oregon 97201, USA

Publisher Summary

This chapter presents a comparison of chorioallantoic and placental respiration. The studies of the dynamics of oxygen supply described in the chapter were started by measuring the total carbon monoxide diffusing capacity of the fertile hen’s egg, using a preparation that was very simple in principle. Several living eggs at a known stage of incubation were placed in a closed system, containing a CO analyzer. Room air recirculated rapidly through the system. After temperature equilibrium to 38°C had been achieved, a small amount of CO was injected into the recirculating air, and its rate of disappearance was measured. Before the sixth day of incubation, eggs have ...

Table of contents

• Cover image
• Title page
• Table of Contents
• ADVANCES IN PHYSIOLOGICAL SCIENCES
• Copyright
• FOREWORD
• PREFACE
• Trends in respiratory research
• Respiratory muscles in man: mechanics and control
• Comparative physiology of respiration: birds versus mammals
• Breathing control during exercise
• Prostanoids in the lung
• Arterial chemoreceptor mechanisms and respiration
• Defense reflexes from the respiratory tract
• Selected papers
• INDEX